import java.util.*;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 石方旭
 * Date: 2022-04-20
 * Time: 18:41
 */

public class TestDemo {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        while (scan.hasNextLine()) {
            StringBuilder sb = new StringBuilder();
            String str = scan.nextLine();
            for(int i =0;i<str.length();++i) {
                int[] count = new int[1000];
                count[str.charAt(i)] ++;
                if(count[str.charAt(i)]==1) {
                    sb.append(str.charAt(i));
                }
            }
            System.out.println(sb);
        }
    }
}
